Single point quantification of antibody by ELISA without need of a reference curve.

A new method for the quantification of antibodies in the enzyme-linked immunosorbent assay is described. This procedure replaces titer determinations based on end-point dilution of the antibody under investigation. Here, the sample is tested in a single dilution and the optical density (OD) obtained is used in the equation log10 titer = alpha.OD beta. The titer can then be calculated by inserting into the formula the values for the constants alpha and beta, which are specified by the manufacturer for each separate batch of kit reagents. This so-called alpha-method saves time and reagents while providing results which are equal to the titration method in accuracy and superior in precision. The alpha-method is also a simpler and reliable alternative to the use of standard or reference curves for the quantification of the antibodies in I.U./ml.